[swift-evolution] [Proposal] Add property for negation to Bool

Charlie Monroe charlie at charliemonroe.net
Sat May 21 09:59:08 CDT 2016

This would make sense as an operator (or actually it would have to be a keywod):

return not self.lanes[...].contains(.Gap)

Or if you don't mind having { } around the expression it could be defined as a function:

func not(@noescape block: (Void) -> Bool) rethrows -> Bool { return !block() }

Then you can have

return not { self.lanes[...].contains(.Gap) }

But I am personally not a fan of this.


> On May 21, 2016, at 4:50 PM, Антон Миронов via swift-evolution <swift-evolution at swift.org> wrote:
> I found negation operator (!) the least detectable among the code. So I’ve decided to add property “not” to BooleanType (Swift 2.2) or Boolean on 3.0 with extension:
> extension BooleanType {
> 	var not: Bool { return !self.boolValue }
> }
> This is code with negation operator:
> 	return !self.lanes[position.y][currentLaneRange].contains(.Gap)
> As I sad before negation operation is hard to spot. Moreover at first it looks like I’m trying to negate self for some reason.
> This is code with “not” property:
> 	return self.lanes[position.y][currentLaneRange].contains(.Gap).not
> Now it is easy to spot the statement I am actually getting negation of.
> On my experience negation operator can occasionally be missed while reading code. This happens less often with “not” property. So I’m proposing to add this property to standard library and prefer it in most cases.
> Thanks,
> Anton Mironov
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

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